Gas tube



Dec. 2, 1952 I w. J. O'BRIEN 2,620,450

GAS TUBE Original Filed April 10, 1941 5 Sheets- Sheet 1 Dec. 2, 1952 w,O'BRIEN 2,620,460

GAS TUBE Cliginal Filed April 10, 1941 3 Sheets-Sheet 2 Dec. 2, 1952 vyJ. OBRIEN GAS TUBE 3 Sheets-Sheet 3 Original Filed April 10, 1941 xOm 50Patented Dec. 2, 1952 GAS TUBE William J. OBrien, London, England,assignor, by mesne assignments, to General Motors Corporation, Detroit,Mich., a corporation of Delaware Original application April 10, 1941,Serial No. 387,908. Divided and this application June 12, 1947, SerialNo. 754,194

11 Claims.

The present invention relates to improvements in stop-on-signal radioreceivers and control circuits therefor including fast-operating, lowimpedance relays, and more particularly to circuits wherein said relaysare controlled by means of gas tubes.

The present invention relates also to the provision of new and improvedstop-on-signal radio receiver circuit arrangements for preventingdeleterious effects resulting from oscillations in circuits includinggas tubes, fast-operating, low impedance relays, and condensers utilizedto provide the relays with current impulses to increase the rapidity ofoperation thereof.

This invention relates also to the provision of new and improved gastubes,- and more specifically to the provision of gas tubes having anauxiliary anode by means of which the gas in the tube is maintainedionized and the tube conductive in spite of fluctuations in anodepotential to values below that at which the gas would be deionized andthe tube rendered nonconductive.

The present invention further relates to the provision of a new andimproved stop-on-signal or stop-on-carrier control for radio receivers,certain forms of which are disclosed and claimed in the Patents ofEdward F. Andrews, Nos. 2,262,218, issued November 11, 1941, and2,326,737, issued August 17, 1943. My Patents Nos. 2,426,580, issuedAugust 26, 1947, and 2,489,721, issued November 29, 1949, and mycopending application Serial No. 681,183, filed July 3, 1946, which isnow Patent No. 2,526,266.

The present invention relates especially to the use of the special typeof gas tube with an auxiliary anode in a stop-on-carrier control systemof the type shown in my above-mentioned patents, whereby the number oftubes required i reduced by one. This application is a division of mycopending application Serial No. 387,908, filed April 10, 1941, which isnow Patent No. 2,442,430, issued June 1, 1948.

Other aspects and advantages of the present invention will becomeapparent from the ensuing description, in the course of which referenceis had to the accompanying drawings, in which:

Fig. .1 is a diagrammatic representation of a control circuit for a fastoperating relay embody-.

Fig. 4 is a view similar to Fig. 3 of another 1 embodiment of the tube;

Fig. 5 is a fragmentary perspective view of a further embodiment of atube constructed in accordance with the invention;

Fig. 6 is a diagrammatic representation of a standard automobilesuperheterodyne receiver, in connection with which the present inventionhas been utilized; and

Fig. 7 is a diagram showing the details of a portion of the circuit ofFi 6.

The circuit arrangement illustrated in Fig. 1

comprises a'relay l0 whose energization is controlled by a gas tube II.In order to effect fast operation of the relay, it is constructed tohave a low impedance and low inductance winding so that with a givenvoltage a large current flow through it will be established in a shortlength of time. The low impedance and inductance are obtained byutilizing low resistance wire and winding having relatively few turns.Reduction of the number of turns reduces the actuating force exerted bythe relay as the number of ampere turns is reduced (assuming the voltagesupplied to the relay to remain the same), and to compensate for thisreduction and to obtain fast operation the relay winding, indicated byreference character [2, is supplied with a considerable current impulseupon energization by means of a condenser 13 discharging through thewinding when tube H is rendered conductive, the discharge fiowingthrough the tube. This discharge of a large current by the condenseroccurs rapidly because of the low impedance of the relay winding and ofthe gas tube, thereby to effect fast operation of the relay. However,the circuit including the relay winding, tube and condenser has atendency to oscillate because of its'low resistance, and theoscillations reduce the anode potential of the tube and are likely tocause deionization of the gas in the tube and to render the tubenonconductive. These fluctuations are prevented from deionizing the gasin accordance with the present invention, as illustrated in Fig. 1, byproviding the tube with an auxiliary anode supplied with a potentialsufficient to maintain ionization of the gas in spite of fluctuations inanode potential. r

In addition to the auxiliary anode, indicated by reference character it,the tube is provided with an anode l5, a grid l6, an indirectly heatedcathode l1, and a cathode heater I8. The physical construction of thetube may take various forms, three forms being shown in Figs. 2 and 3,4, and 5. In the embodiment of Figs. 2 and 3'the tube is shown with theusual glass envelope l9 and base 20. The envelope surrounds thepreviously enumerated elements of the tube and contains an ionizablegas. The anode I5 is cylindrical in shape and is supported inconventional manner by a pair of spaced posts 2! between insulatingplates 22. The cathode I! is cylindrical in shape and supportedconcentrically with respect to the anode by a refractory post 23 inwhich the cathode heater I8 is embedded. The grid it is a helical wirelocated in proximity to the cathode and concentrically arranged withrespect to both the cathode and anode. The auxiliary anode M is also ahelical wire, it being located in this embodiment in proximity to theanode and concentric with respect to the other tube elements. Suitableleads are brought from the tube elements to prongs on the tube base 20.'All the tube elements are of substantially the same-length in orderthat the tube may operate in its intended manner, as will be describedshortly in connection with Fig. 1.

The tube illustrated in Fig. 4 is similar to that just' described exceptthatthe grid and auxiliary electrode are constituted by metalliccylindrical members 25 and 25 provided with two or more alignedapertures 26 and 21, respectively.

The tube illustrated in'Fig. 5differs from those previously describedmainly in that the grid and auxiliary anode are constituted by aperturedflat structural elements 230 and 23!, respectively, and the anode by acylindrical wire 232'. These elements-and the cathode 233 and cathodeheater 234 are surrounded by a grounded metallic shield 235, the openends of which are closed by insulating plates 236. The shield comprisesan apertured partition 23! located between the grid and-auxiliary anode,thus defining two compartments, one for the cathode, cathode heater andgrid and a second for the auxiliary anode and anode. The apertures inthe grid, partition and auxiliary anode are in alignment with each otherand the cathode and anode. A tube of this construction may beconstructed simply and economically and possesses a high control factor.

Returning now to a further detailed description of the circuit of Fig.1, it may be seen that the relay winding 12 is composed of two seriesconnected coils. One terminal of the winding is connected directly toanode 15 by conductor 23 and the other to the positive terminals of asource of potential, such as battery 36, through a current limitingresistor 3| and conductors 32 and 33. The battery thus'serves as asource of anode potential for the tube and as a source of energizingcurrent for the relay. The other terminal of the battery is groundedthrough conductor 34.

The power consumption of the relay is reduced by the resistor 3! whichis chosen to have a value such that once the relay is energized, thecurrent flow therethrough is only sufiicient to maintain the relay inits operated position.

The current impulse supplying condenser I3 is connected to the cathodeby conductor 35 and to a point intermediate the relay and resistor 3| bya conductor 36. It is thus connected so as to be charged by battery 30when the tube is nonconductive and to discharge through the tube andrelay when the tube is conductive.

The auxiliary anode is supplied with a potential sufiicient to maintainthe gas ionized and the tube conductive in spite of fluctuations inanode potential from a suitable source, preferably the battery 30,through a current limiting resistor 31 and conductors 38, 39 and 33.

Grid-bias voltage is obtained through the use of an adjustable resistor40 connected between the cathode and ground. This resistor is connectedto the cathode by. conductor 4| and to ground '4 through switch 42 andground connection 43. The grid is connected to ground through conductorit, resistor 45 and conductor 46. A gridbias voltage sufhcient normallyto maintain the conductors 48.

The relay'may be utilized to control circuits or mechanisms and thelike. In stop-on-carrier controls it is utilized to control circuits anda clutch, asindicatedin Fig. l. The relay may also take variousforms,that shown in Fig. 1 being of a novel construction requiring butlittle space. It comprises a metallic base 49 having an upturned flange50 at its front end- The coils l2 together with their cores 51 aresecured to the flange. The cores have upturned ends above which issupported an armature 52 mounted at the ends of contact carrying switchblades 53 and 5 1. The switch bladesare 'biased-upwardlyinormally tocomplete circuits through fixed switch blades 55 and 56 and are movabledownwardly upon energization of the relay to completecircuits throughswitch blades 51 andy58prespectively. The switch blades as well astheterminals to which conductors 28 and 32 are attached are mounted atthe rear of base 49, by spacer blocks 59 and suitable bolts. The spacerblocks-are made of insulating material toinsulate the'terminals andswitch blades from one another.

Switch blades 53 and 54 are'biased upwardly by a spring 63 that servesalso to maintain the clutch engaged whenever the relay is deenergized.The biasing is effected through a combined clutch operating and powertransmitting rod 6| slidably and rotatably mounted in a supportingbearing 62 forming part of the base member. The spring is held betweenthe bracket and a washer 63 secured to the rod above the bracket.

The clutch comprises a pair of selectively engageable-elements 5'4 and65, the former of which is secured to rod 6 l and the latter of which isdriven from a suitable source of motive power, such as an electricmotor, by gear'fia. When the clutch is engaged, rod 6| rotated to impartmovement to a driven gear 67 used to drive tuning condensers instop-on-carrier controls, as will be explained more fully in connectionwith Figs. 6 and 7.

In the description of the operation it is assumed that the tube isnonconductive by reason of the bias applied to grid 16 and that, as aresult, relay It! is deenergized. At this time the grid is biasednegatively by reason of current flow through resistors 46 and 41, whichare connected across the battery 36 through conductors 33' and 39,switch 42 and ground connections 34 and43. The condenser I3 is fullycharged by reason of its connection to the battery and batterypotentials are applied to auxiliary anode l4 and anode [5.

The tube is rendered conductive and the gas therein ionized when apositive signal of sufficient strength is applied across resistor 45,after which the grid l6 becomes inefiective to exert further control.Immediately the tube is rendered .conductive, current flows throughthe'relay windings I2 and fast operation of the relay is. insuredbyreason of its low resistance and impedance and the discharge ofcondenser 13 therethrough; The

low'resistance' series circuit including the condenser, tube and relaywinding-has a tendency to oscillate'with the result that thepotentialapplied to anode I may be periodically reduced to a value 'belowthepotential required to maintain ionization. In the ordinary threeelement gas tube the result would be the deionization of the tube',"butin the described apparatus, the gas' in the'tube is maintained ionizedby the auxiliary anode I4, which is connected to the battery throughresistor 31 and which is not effected by the oscillatory circuit.

The'relay is supplied with current sufficient to maintain it energizedthrough a circuit including the battery, ground connections 34 and43,-the tube and resistor 3|. Resistor Si is so propor tionedthat itlimits the relay current to the desired value. Resistor 31 is soproportioned that only a very limited amount of current flows throughit, thereby reducing power consumption by "preventing any substantialflow of current through it and the auxiliary anode in excess of thatrequired to maintain ionization.

When it is desired to deenergize the relay and to render the tubenonconductive, it is necessary only'momentarily to open switch 42.Opening of this switch results in the opening of both the anode'v andauxiliary anode circuits as the switch is in series with the tube andbattery.

' The present invention is particularly adapte for stop-on-carrier radioreceiver control. The use of a gas tube provided with an auxiliary anoderesults in a reduction of the number of tubes required. For instance,when used in a control of the type disclosed in my copendingapplication, one tube is eliminated. An application of the tube to thistype of control is illustrated in Figs. 6 and'7. Referring now moreparticularly to Fig. 6, it may be noted that this figure illustrates inblock diagram form a standard automobile superheterodyne receiver towhich the elements of the present invention have been added. For themost part the receiver and control circuits are those disclosed andclaimed in my Patents 1 Nos. 2,426,580, 2,489,721, 2,442,430, and mycopending application Serial No. 681,183, previously mentioned, andconsequently only the portion of the circuit associated with theoperation of the novel gas tube of the present invention will bedescribed in detail hereinafter. r

The receiver comprises an aerial II3, a radio frequency stage I I I, afirst detector and oscillator section I I2, an intermediate frequencystage I I3, a second detector section II4, a balanced bridge circuitsection II5 forming part of the stop-oncarrier-control and illustratedin greater detail in Fig. '7, gas tube II6 also forming part of thestop-on-carrier control, a volume control potentiometer II I, an audiofrequency amplifier section H8, and a loudspeaker H9.

Energy is supplied by a battery I20 adapted to be connected by a switchI2I to a tuning means operating motor I22 of the reversible type, acathodeheater circuit I23, and through an interrupter, step uptransformer and B supply unit I24 to a B supply line I25. The B supplyline leads to the various receiver portions and the stop-on-carriercontrol in a manner to be considered in great detail hereinafter. Theswitch I2I is illustrated as a manually operable switch, but it may beoperated by the motor I22, as set forth in my copending application.

The receiveris provided with the usual tuning condensers I26 which areactuated by motor I22. The tuning and receiver volume are controlledfrom 'a remote point, such as the dashboard of an automobile, by meansof a tuning control switch I21, which is normally closed, and a volumecontrol switch I28, which is selectively operable from a normal circuitbreaking position (into which it is biased as by springs) to the left toincrease the volume and to the right to decrease the volume. Beforedescribing in detail the various control means and control circuits, itmay be well to review briefiy the mode of operation of stop-oncarrierradio receiver control. In so far as tuning is concerned, the tuning isinitiated manually at the remote point by momentary opening of switchI21. This sets the motor in operation to rotate the tuning condensersthrough a clutch until the receiver is tuned to the carrier frequency ofa station received with a certain intensity. The motor operates first inone direction over the entire range of movement of the condensers andthen in the other, the direction of rotation of the motor beingcontrolled by limit switches cooperatively associated with the condensershaft. The same motor is used to control the volume but, when so used,it is selectively operable in either direction upon operation of switchI28 to. either of its two positions. volume control also includes aclutch through which the motor is selectively connected to the movableportion of the potentiometer II'I heretofore referred to.

Referring again to Fig. 6, it may be noted the condensers I26 aremounted for rotation with a shaft I30 connected by gears Him a shaftI32. The latter is adapted to be connected to a shaft I33 driven bymotor I22 whenever a relay I34, associated with the stop-on-carriercontrol, is deenergized or released, at which time the clutch I35 isengaged. The relay and clutch may be constructed in accordance withthose illustrated in Fig. 1, i. e., the relay is of the fast acting typeand the clutch is operable by the relay armature. The energization ofthe relay is controlled by gas tube I I6 and when it is energized,

shafts I32 and I33 are disconnected to prevent further driving of thecondensers whenever a station received with a certain intensity is tunedin. As already indicated, the tuning condensers are rotated first in onedirection and then the other, the direction of rotation being reversedat .the limits of their movement by a limit switch I36 operated by twoarms or the like I31 suitably secured to condenser shaft I30.

The volume control includes a clutch I38 operable by a relay I39 andadapted whenever the relay is energized to interconnect shafts I33 andI40. The latter isoperatively connected to the movable member ofpotentiometer I II.

The motor I22 has a pair of windings MI and I42 selectively energizableto rotate the motor in opposite directions. Winding MI is connected byconductors I43 to the right contact of volume control switch I28 and bybranch conductor I44 to one of the two contacts associated with limitswitch I36. Winding I42 is connected by conductor I45 to the leftcontact of the volume control switch and by a branch conductor I46 tothe other contact of the limit switch. The movable blade of volumecontrol switch I28 is connected by conductor M1 to one terminal ofclutch operating relay I39, the other terminal of which is grounded.Thus, when switch I28 is operated to either of its two positions, themotor is energized simultaneously with energization of V the relay and,as a result, the movable member of the potentiometer is operated in onedirection The.

orathe other 'tOfiHCITBflSBLOI. decrease-the volume.

of :reception. The, energizing, circuit is completed inboth casesthrough the-armatureof motor I22,

switch ;I2I,, battery I.20J and ground.

Theiremotetuning control switch .121, which is opened. to. initiate thetuning of another 5132-.

tion, :has one of its fixed contacts connected to.

conductor IA], this conductor serving, as will appear more-fullyhereinafter, :as a ground-conned.

tion, and its other fixed. contact connected to adjustable resistor LI4B. Aiconductorilfl connects the latter to the cathode of .gas tubeI;I.fi:whereby the switch and resistor .areincluded .in. the platecircuit 'ofthe stop-on-carrier gas tube ISIS.

The .energization of motor I22. during tuning is controlled by .relayI34 which .actuates .switch blades I50 and I51. Switch blade 15!]: hasassociated with it a .pairof relatively fixed switch blades I52 and I53,while blade .I 5.! has associated with it .a, relatively fixed blade.154. Blades 15% and "I5I, areconnected to. groundby conductor I55.Blade I52 is connected Itolimit switch I35. Blade .153 .is connectedzbyconductor lfificand an AVG delay condenser I51 :to .an AVC'conductor.

I58. .Blade I54 is connected .by conductor I59to- I41 or 142 depending.uptontlreiposition of limit switch .I-.36,;switch .blaides. I52 .andI51 ,and. ground connection I55 b'ack'to the battery. .At thesame timeconductor-I56 and condenser I5! are disconnected :from ground to:provide fast acting AVCiasdescribed inzmy copending application), whileconductor, I59 is connected to ground through switch blades I51 and I54andconductor 155. Connection .of conductor I59 to ground serves toconnect the gridsiof the. amplifier tubes of the lastamplifier(audio-frequency) .to ground to mute the loudspeaker during tuning. Whenthe relay is energizedby tube I Iiibecoming conductive, as .now about tobe described, the condensers are declutched from the motor and :thelatter deenergized. The motor is .deenergized by reason of the openingof its energizing circuit by disengagement :of blades .ISELand I52. TheA-VC delay condenser I5! is simultaneously rendered efieotive 1160increasethe time :delay applied to the .AVCyoltage toa value "necessaryfor proper .treception during normal reception. Furthermore, thetgroundis removed from the audiofrequency amplifier tubes. to condition thesefor normal operation.

The primary function of gas tube 11.6 is to control the energization ofrelay I34 so that it is substantially instantaneously operated when thereceiver is tuned to the carrier frequency of a broadcast station. Afurther function of this gas tube, which is provided with .an auxiliaryanode H1, is to employthe high positive control voltage impressed ontheauxiliaryanode 130.}3167 vent premature deionization of thetuhe as aresult of oscillations .in the plate. circuit after, it has beenionized. To fulfill this function,'the

gas tube I.I6 operates ;in a .manner somewhat similar to that describedin connection with Fig. 1. The relay is energized when the tube isrenderedconductivexand the latter is rendered con-- ductive wheneverthecondensers. I26 :aremotated age to be referred to later.

to tune. the. receiver to. carrierireqnencymf a broadcast station, Toinsure the 'tubebeing rendered conductive :wheny'the station inexact.-ly tunedin, the tube is controlled .in response to the. tuning. Inbrief,;the tube 1 I6 is controlled by two potentials, oneacting upon theauxiliary anode I11! and the other upon :a :grid 2 -12.. Thesepotentials. vary with the tuning of the receiver and render the tubeconductive :when the station is substantially exactlytuned: toogcarrierwfrequency.

Referring now more particularly to Fig. 17;, this figure illustrates .ingreater -;detail:.certa1 portions of the apparatus illustrated diagram.-maticallyin Fig. 6. These portions are: those from which the controlpotentials for the gas. tube are obtained. Corresponding :elementsnoi-Figs. 6 and 7 are indicated by like. reference characters.

The radio .frequencysection- I-Irl. of :6yi5 shown to comprise .atubeqfll. Its :controhg d is coupled in conventional manner 170517118 lantennaby conductor-I12 and connected :to, the

AVG conductor I58: through resistor II3., Its anodeis-connected to theprimary winding 1-14 of a, coupling. transformer which has. not :been,

illustrated in full but which is utilized to :con-

necttubeg'lll to the first detector. and oscillatorsection I I2, whichlikewise .has tnot. been; illustrated in Fig. 6. Elle -terminaloi?'-.windingyfI1;-I4

remote .from the anode is connected to .the; .B" supply conductor Ithrough conductor. .1 151311121] resistor :I'iSand-tothe-.auxiliaryaanodeIFI-TI of ithe gas tube through conductor H5 iandqaresistor 17:8. The same terminal is also :by-passedto ground throughcondenser. 111A.

The automatic, volume .controlmcludes {a sistor I119 connected between,aconductor. I 53 :andv

asconductor I leading to" a source -:of AVC'wolte.

very small radio frequency by-IDaSS, condenser I81 connected betweenconductor ;I5 8:and,zground and the previously mentioned AVG time delaycondenser 15! that is controlledfby switch blades;

I59 and I53 operated .byrelay 134.

The outputv .from the 'IadiOvfIBQJlBIICX "section I I I .is, as already,described, supplied-to :the first detector and oscillator section 1|I2,:and thence to the intermediate frequency section [13,, A. portion ofthe output from the latter :is supplied to the second detector stage I14and :a portion to the balanced bridge circuit ;and-stop,-;on-. carriercontrol section 11.5.

The intermediate frequency section comprises a tube I32, the anode ofwhich-ls connected to one terminal of the-primary *windingIB3 of..:a

closely coupled transformer, the other terminal,"

of which is connectedto B-supp ly-conductor I25. A portion-of'the outputof'tube I82 45 sunplied to the detector stage through the secondarywinding I84 of the :transformer. Oneterminal of winding. 1 84 isconnectedi-to the detectorganode.

I85 of a multi-fiunction tube. IB6 .through-;:con-

ductor I81, and the otherterminal by rconductor I88- to volume controlresistor I-I 'I, whichisv frequency amplification. Its control grid- 92is.

connected to the movable .member of the volume control potentiometerthrough a suitable .source of grid biasing potential,,:such;as battery193 It .also, :includes .a.

further connected to ground by a grid leak resistor I96. Theamplifiedaudio-frequency output is supplied to the succeeding stage ofamplification through the anode connection I91.' From the foregoingdescription it may be noted that the circuit of Fig. 7 does notcorrespond exactly to the block diagram of Fig. 6, in that in the,latter the second detector and audio- !requencyamplifier sections havebeen entirely separated. However, in a practical installation the tubeI86 may well perform the dual function of a detector and amplifier, andit has been illustrated as doing this in Fig. '7. As a matter of fact,and as will appear shortly, tube I86 is utilized also as a rectifier toprovide a second conand 2,489,721, previously mentioned. This circuitcomprises a first tank circuit including primary winding I83, condenser20I, condenser 202,

" resistor 203, and an adjustable condenser 204,

whereby this circuit may be tuned to resonance at the intermediatefrequency; The circuit also comprises a second tank circuit includingcondenser 202, inductance coil 205'and an adjust able condenser 206 fortuning this tank circuit to resonance at the intermediate frequency.

The commonxc'onnection of condensers 20I, 202 and 206 is grounded. Thecommon side of winding I83 and condenser 204 is connected to the common,side of inductance 205 and condenser 206 through condenser 201.

The output from the bridge circuit is led to the anode 208 of the seconddiode rectifier section of tube I86 through a condenser 209 andconductor 2I 0, and the rectified output appearing as avoltage dropacross resistor 2 is supplied to the control grid 2I2 of gas tube I I6through a time delay circuit including 'the resistor 2I2 and condenser2l3. The resistor 2I2 is in series with the grid lead 2 l4 connectingthe grid to the anode end of resistor 2 I I. A radio frequency bypasscondenser 2I5 is connected across ground conductor I 9| and thepreviously referred to conductor I49 leading to the cathode 21s of gastube '6. v 1

The relay I34 is connected to anode 2 I8 of tube II S by conductor 2I9and the B supply is connected tothe anode through the relay winding andcurrent limiting resistor 220. A current impulse-is supplied to therelaywinding when the tube is rendered conductive by a condenser 22I havingone terminal connected to the cathode 2l6 through conductor I49 and itsother terminal connected to a point intermediate relay winding I34 andresistor 220. A bleeder resistance 222, connected at one end to the Bsupply and at the other end to the cathode lead I49, provides properbias of the grid 2I2 when the tube is nonconductive, current flowingtherethrough and the previously mentioned bias adjusting resistor I48. I

The operation of the system of- Figs. Sand '7 is swi q Ibl des. MB" aedbek t ii tery through ground connection I 55; Since clutch I35 is engagedwhen relay I34 is deenergized, as it is at this time, the motor rotatesthe condensers I26 first in one direction and then the other as thewindings MI and I42 are alternately energized by operation of limitswitch I36 from one position to another by the arms I31 mounted oncondenser shaft I30. This rotation of the condensers in alternatedirections continues until the various tubes are heated and a broadcaststation received. When a station is received, the gas tube H6 isrendered conductive and relay I34 immediately operated to' declutch thecondensers from the motor shaft and to deenergize the motor.

The gas tube is rendered conductive by the application of an increasedpositive potential on the auxiliary anode I11 and by a reduction of thenegative voltage impressed on the grid'2l2 from the diode 208. Theauxiliary anode is made more positive as a result of the application ofautomatic volume control voltage to the grid of radio frequency tubeI1I. This control voltage is obtained from the second detector sectionof tube I86 and is applied to the grid of tube '-I1I through a circuitincluding conductor I80, resistor I19, conductor I53, resistor I13, andconductor I12. As a result of the'application-of this control voltage onthegrid of tube I1I, the plate current of this tube is decreased, withthe-further result that the voltage drop across resistor I16 isdecreased and an increased positive potential is applied to theauxiliary anode I11, which is connected to the anode side or resistor I16. This connection is through resistor I18 which serves to limitcurrent flow through the auxiliary anode. The voltage applied to theauxiliary anode rises rapidly as a s-tationis being tuned in and is at amaximum'when a station is exactly tuned in, as described at considerablelength in my Patents 2,426,580 and 2,489,721, previously mentioned.

The voltage thus applied to the auxiliary anode I11 whenionization'occurs is considerably in excess of the ionizingpotentialpand remains so until the next station is tuned in by. manuallyoperating push button switch I 21, to 'deionize tube H6. Thus, eventhough oscillationf'in the circuit, including tube H6, relay I34, andcon denser 22I, may reduce the voltageof the plate 2I9 below ionizingpotential, ionization is-mainpotential until the switch I21 isagainopened.

The balanced bridge circuit 200 supplies asignal to the diode 208 whichincreases as resonance with the station is approached until it :iswithin about one kilocycle of resonance. 0 From this point the amplitudeof this signal falls .rapidly,

substantially to zero. -Thus, a negative direct current voltage from thediode 208 is applied to the grid 2I2 of the gas tube 6, which-increasesas resonance is approached to a maximum negative value around onekilocycle from resonance,

and then falls steeply substantially to zero at resonance. The reductionof this negative signal on the grid 2I2 when the station is correctlysition correctly to tune in the station.

The primary winding I83 of thetrans'iormer .associated withtheintermediate frequency tube enser:;206. is.substantially zerojwhen asignal of xactlyi-intermediateffrequency is placed: across H the.primary .windirxgtitl. In otherwords; the reflect of? the couplingoccurring-..through-.,con- 1 denser? 201 produces avoltage drop-acrossthe in-: ductance-205 whichis equal and opposite .t0,ithe .voltagei-dropacross :condenser202 at; resonance. z;-'. :The valuerofre'sistanc'e 20-3isselected so* as to bring: thevoltage across .the condenser 2 02, 180utxof phase-with thexyoltagez across inductance 05.".Undertheseconditions-there is substantially eroiyoltagaacrosscondenser=2fl6 atresonance. In;-:onertaspectwthe; arrangement of thecoupled ircuitszmay'be considered as a-balanced bridge 150n1;the."otherahand, ifvthevsignal" across the primary winding- |83slightly-out of resonance, hereis n'oilonger a balance'betweentheopposing reater;:.than:that otthe-other, and a potential aryingwith-:the ideparture fromresonantfreuency :exists ;:acrosscondenser-205. When the ondensers l 26" are: 2approaching.iexact :tuning, that.is;yne Or'ItWO-kiIOCyCIGS :away from: exact tuning, a. very :large;alternating i currentj voltage is applied to the anode 208*ofthe:rectifier section. The'routput'of;the rectifier-appears as a; 'voltagedropracrosst resistorflIl :anduthistvoltage is appliedrthroughrresistor'2l2fl to the grid.;2l2 of. ubeZlGJi The greater theiyoltageappliedto'the armament therectifier, themore negative. the grid ZIZ.

: The normal negative. loias ofith'e grid 2 I2 due istance '222 is suchas to renderetheltube-conductive when thenegative bias applied to thegrid' '2 [2 from: the balanced bridge; circuit and rectifier approachesa" minimum valve (which occurs 'at resonance'l Sothatwhen :a-station isexactlyrtuned in; the tube is rendered conductive by -the conjoint'action's of the less negative grid and-" morepositive auxiliary anode111. When the tube flfi-isionized', the plate to cathode resistance oi-the tube drops to a relatively low value? The condenser 221 whichaccumulates a 'high ch'arge through'its connection to the B-supplythrough resistor 22!) during the nonconductive period of I tube 2[6-, now discharges rapidly through the low impedancewinding of relay134, with the further resultthat-the relay 'is' instantly operated to'-declutch the condensers from the motor'shaft and to deenergi'ze themotor, "'--*thus*stopping the-condenserexactly on-the car: rier"frequency" as previously explained. The ""steady flow of current throughthe resistor22ll, relay winding'and tube, which" are connected in tankcircuits, the potential appearingacrosscon-v 15 circuit oravcircuitaproviding-zeroacoupling at 30 'couplings-ethat is, theeffectof-onecoupling is 35 v: to th'e:biasing -resistor lw and thebleeder re 50 series =across-theB"" potential, is sufficient to hold 7 I5312 *As heretofore explained, ;-the operation. of'zrthe ...z-sw.itchofsrelay, 134 results ;also intthee-disconl. nection oi conductor A afrom :ground, thereby r removing ,thelground .connection. from the "last5-- '-;;stage. oisaudio -f;requency amplification,i-andpthe (output oithe receiver can be heardthrougl-rloudspeakerl l 19,, llhe relayualso;-efiects connection 10f ,switch-.;blades I 50 rand l 53, nwith the.result ;:that condensencl5l. is .connected. torground to 10-;renderit,:efiective. to increase; the. time; delay applied tcrthe automaticyolumeccontrol voltage necessary:- .for 1 proper, .qualityreceptionsd-unng l,.,..,taudible; reception xof-the signal.

-,=When ,it desired: to; tune inzaiidifferent; sta- 32,- ion, ;switch;rI21 iis. momentarilyppened; thereby l-lzefieotiyely gbreakm theplaitecircuit.v of the ;gas tube which results inithesdeenergizaticn:cfaielay :l 34;:{I'l1emotonis thereby energizedandz-the con- EdEIISBIS THEEQCOIIHBCBBQ to, the motor-shaft: :The tuningoperation described above will be repeated ,and-s,thei motor-again;-deenergized; and: the icon- .3 drawers edeclutched upon reception": of:another gsignalexceeding-acertain rstrength. tiThe :signal Mi---strength at which-.the..:tuning meanswil-l-roperate 25: may -beiadjusted at @Will by-means ofztheadjustai ble resistor, 1 48 whichserves to control thenormal --negative.bias ofbthe grid 21 2 Of$th9fgaSjtub9.

f Thewolume may-becadjusted"at anyrtime by zr movingrtheivolumecontrolzswitch: l28-z'ieitherto lcthe-sright-or left, astindicated inFig. (ii-#When '"move'd'into eitheri'ofrits :circuit makingzpositions,thecone orathenother of: motor windings I41 or I42: is g;energizedvsimultaneously with: the enera ."1 :er ization of: clutch zoperatingsolenoid I39." The :.r:energization of the solenoid; results in the:clutchfixing of rthefvolumeicontrol-i shaft Into. the motor shaft I33,with theIresult .thati.the movable memberofzthewolumecontrolipotentiometerl I1 iseoperatediinthe.directionselected by-operation of hevolumecontrol switch"I 28.

When'it isdesired to turn the receiver'off, it s-l-necessary only toopen' -the'power switch' I21 whicheliectively cuts offthe power to theradio receiver: proper and -to the various controls.

1 T Although the invention has been disclosed in connection" withspecific details of preferred embodiment's thereof, itinust'vbe'understoodthat suchg'details'aremot intended to be limitative of -theinvention-exceptin so 'far as. set forth in the accompanying claims.

..,Havingthus described my invention iwhat I claimas.newoand,desiretosecure by Letters .Pat- .;entioif=thellnitedfitatesis:

5 A gags-tube,roilthetypapassing.asubstantial aspacecurrentwhenionizedand-.a'hegligibleispace current .--.when deionized :andhaving avcathode, an .anode :surrounding- -said r-cathode', ;a, grid- 10- 1;cated-in proximity to? andsu-rrolmding said cath- 110618,? :and ran:auxiliary; anodersurroundingi. said grid. and: zlocatedzrbetween; the:latterxandisaid 1 anode, said auxiliary :anode being connected andarranged to control or maintain :the ionization ofs'aid tube. 6 2.A-gastube including-incombinatiomacath- 1 odehavinga substantiallycylindrical exterior, an anode having a substantiallycylindrical-interior spaced *from i and 1 located substantially:concentrically with respect to said cathode, agrid'comprising a woundwirehelix located in proximity to andsubstantially concentrically'with'respect to "said. cathode-, an'd' anauxiliaryanode comprising awound wire =heli-x:located betweenandspaced from-said anode andgridand-arranged substan- -tial-1y concentrically with respect thereto.

3. A'gas tube, including in combination, a, cathode having asubstantially cylindrical exterior, an anode having a substantiallycylindrical interior spaced from and located substantiallyconcentrically with respect to said cathode, a grid comprising a metalcylinder located in proximity to and substantially concentrically withrespect to said cathode, and an auxiliary anode comprising a metalcylinder located between and spaced from said anode and grid andarranged substantially concentrically with respect thereto, said gridand auxiliary anode being apertured for the passage of electrons andions.

4. A gas tube, of the type passing a substantial space current whenionized and a negligible space current when deionized and having acathode, an anode, a grid, and an auxiliary anode, said grid andauxiliary anode comprising plates having aligned apertures, said platesbeing spaced apart from each other and from the anode and cathode, saidauxiliary anode being connected and arranged to control or maintain theionization of said tube.

5. A gas tube, including in combination, a cathode, an anode, a grid,and an auxiliary anode,

said grid and auxiliary anode comprising plates having alignedapertures, said plates being spaced apart from each other and from theanode and cathode, and a grounded shield surrounding said tube elements,said shield having an apertured partition located between the grid andauxiliary anode.

6. A gas tube, including in combination, a cathode, an anode, a grid,and an auxiliary anode, a shield surrounding said cathode and grid andseparating them from said auxiliary anode and said anode, said shieldbeing apertured to provide a passage therethrough from the cathode tothe anode side.

7. A gas tube as claimed in claim 6, wherein the grid and the auxiliaryanode are located on opposite sides of the shield and. adjacent theaperture.

8. In a trigger type gas tube constructed and arranged to pass auniformly high space current when ionized and negligible current whendeionized, a cathode carrying said high space current, a grid located inproximity to said cathode, an anode spaced from the grid on the sideopposite the cathode carrying said high space current,

and an auxiliary anode located between said grid and said anode carryingat least a part of the current carried by said cathode when ionized.

9. A gas tube having a cathode, anode, grid, and auxiliary anode, aconductive shield, partitioning means separating the space within theshield into two compartments including means defining an openingconnecting the spaces in said two compartments, said cathode beinglocated in one of said compartments, a grid in the shield compartmentcontaining the cathode positioned between the cathode and thepartitioning means, an anode in the other shield compartment. and anauxiliary anode in the compartment containing the anode positionedbetween said anode and said'partitioning means.

10. A gas tube as claimed in claim 9, wherein the grid and auxiliaryanode are apertured so that a straight line connecting the cathode andanode will pass through both apertures and through the opening betweenthe compartments.

11. A gas tube as claimed in claim 9, wherein means is provided in thetube to connect the shield and the cathode.

WILLIAM J. O'BRIEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,653,544 Brown Dec. 20, 19271,905,034 Marden et a1. Apr. 25, 1933 1,938,211 Biver Dec, 5, 19331,984,479 Heany Dec. 18, 1934 1,989,461 Ruven Jan. 29, 1935 2,032,137Lubcke Feb. 25, 1936 2,044,619 Livingston June 16, 1936 2,080,235 SmithMay 11, 1936 2,098,331 Bowman Nov. 9, 1937 2,106,847 Kniepkamp Feb. 1,1938 2,185,852 Klopprogge Jan. 2, 1940 2,228,276 Le Van Jan. 14, 19412,398,772 Cone et al. Apr. 23, 1946 2,409,855 Hillyer, Jr., et a1. Oct.22, 1946 2,426,580 OBrien Aug. 26, 1947 2,428,048 Stutsman Sept. 30,1947 2,443,205 Stutsman June 15, 1948

